Compound IA, which is described and claimed in copending application Ser. No. 07/495,199 and having the formula (IA) (SEQ ID NO:1) ##STR2## is a phosphorylated derivative of a natural product which is useful for the control of certain fungi and also for the control of parasitic Pneumocystis carinii as subsequently described.
The natural product from which Compound IA is derived is produced under certain conditions on the cultivation of Zalerion arboricola ATCC 20957 and may be represented by formula (A) (hereinafter Compound A; SEQ ID NO:1). ##STR3## Compound A has a base-sensitive hydroxyl group in the 5-position of the ornithine component of the cyclopeptide, hence, in the normally preferred procedure for ester formation, the hydroxyl in the 5 position has been protected with benzyl ether formation followed by reaction elsewhere. Thus, the compound of formula (IA) (SEQ ID NO:1) has been prepared by forming the benzyl ether (SEQ ID NO:1), followed by phosphorylation to form a dibenzyl phosphate (SEQ ID NO:1), then hydrogenolysis to remove the benzyl groups from the phosphate, according to the following sequence of reactions. ##STR4##